(Acacia Catechu, _Extractum_.)
_Catechu_; olim _Terra Japonica_.[456] _Japan Earth._
QUALITIES. There are two varieties of catechu in the market, the one of
a light yellowish, the other of a chocolate colour; they differ only in
the latter having a more austere and bitter taste. CHEMICAL COMPOSITION.
Tannin, a peculiar extractive matter, mucilage, and earthy impurities.
SOLUBILITY. It is almost totally dissolved both by water and spirit.
INCOMPATIBLE SUBSTANCES. Its astringency is destroyed by alkaline salts;
and precipitates are produced by metallic salts, especially by those of
iron; and with gelatine it forms an insoluble compound. MEDICINAL USES.
It is a most valuable astringent. FORMS OF EXHIBITION. In infusion,
tincture, or powder. (_Form. 51, 52, 58, 151._) In the form of a
lozenge, from its gradual solution, it may be very advantageously
applied in relaxed states of the uvula and fauces; I have found this
remedy successful in cases where the _sulphate of zinc_ was inefficient.
From its great astringency it also forms an excellent dentifrice,
especially when the gums are spongy; for this purpose I have employed
equal parts of powdered catechu, and Peruvian bark, with one-fourth the
quantity of the powder of myrrh. DOSE, grs. x to ℈i. OFFICINAL PREP.
_Infus. Catechu_, _Tinct. Catechu_, L.E.D. _Electuarium Mimosæ Catechu_,
E.D.